In this video, iridescent patches of skin change hue when nerves near the fin are
stimulated. The signal travels through a network of nerves in the skin,
allowing the squid to cycle through a range of hues from blue to red in about 15
seconds. They also change colour via a similar mechanism that alters pigment-containing cells, but the animals are able to display different opaque hues much faster.

The experiment shows that rather than being a local reflex, the central nervous system
controls changes in shimmer. But how squid pick and maintain their skin colour
is still a mystery. The hue of the shimmer helps the animals camouflage themselves - but
they are colour blind, so scientists are puzzled by how they know they've
got it right.

Articale says:- "....but they are colour blind, so scientists are puzzled by how they know they've got it right."

Perhaps in addition to the eye there are a few scattered cone-shaped detectors dotted about the surface such that the skin is capable of detecting hue albeit only in very low resolution. Not so much "seeing" as just an awareness that a certain area of skin is trigger is "brownish red".

Other creatures have light sensitive parts other than eyes, might it seem logical, if they are certain that the eyes are monochromatic only, to hypothesize that squid might have other light sensitive parts too?

Think Again
on August 16, 2012 1:59 AM

Administering electric shocks to a poor squid for this "Research". Great! Hope you enjoyed the video.